This invention relates to catheters and more particularly to steering mechanisms that allow the catheters to be guided through the blood vessels of a patient.
Physicians make widespread use of catheters in medical procedures to gain access into interior regions of the body. It is important that the physician can control carefully and precisely the movement of the catheter within the body, especially during procedures that ablate tissue within the heart. These procedures, called electrophysiological therapy, are becoming more widespread for treating cardiac rhythm disturbances.
During these procedures, a physician steers a catheter through a main vein or artery (which is typically the femoral artery) into the interior region of the heart. The physician then further manipulates a steering mechanism to place the electrode carried in the tip of the catheter into direct contact with the tissue that is to be ablated. The physician directs radio frequency energy into the electrode tip to ablate the tissue and form a lesion.
Since the heart is formed from several asymmetrically shaped chambers, cardiac ablation especially requires the ability to precisely bend and shape the tip end of the catheter to position the ablation electrode within the heart.
A steerable medical device constructed in accordance with the present invention comprises an elongate tubular body having a proximal end and a distal end. The tubular body has a first stiffening member with a distal end that extends from the tubular body proximal end to a first point on the tubular body, and a second stiffening member extending from a second point on the tubular body to a third point on the tubular body.
The second point on the tubular body may be distal to the first point and may also be the distal end of the first stiffening member. Preferably, the first and second stiffening members are formed from compression coils.
The tubular body may further comprise a center support wire and the steerable medical device may further comprise a steering assembly and a first and second steering wire for selectively bending the tubular body in a first direction into a first configuration and in a second direction into a second configuration. The first and second configurations are preferably functions of the lengths of the respective stiffening members.
In an alternate embodiment, a steerable medical device constructed in accordance with the present invention comprises an elongated tubular body with proximal and distal ends. The tubular body comprises a flexible sheath, which defines a lumen, having an inside surface and an outside surface, a first stiffening member extending from the tubular body to a first point on the tubular body, and a second stiffening member extending from a second point on the tubular body to a third point on the tubular body. The second stiffening member is attached to the inside surface of the sheath. Additionally, the steerable medical device may further comprise a center support wire extending from a distal end of the first stiffening member and a third stiffening member extending from a fourth point on the tubular body.
In a further embodiment, a steerable medical device constructed in accordance with the present invention comprises an elongated tubular body with a proximal end and a distal end. The tubular body comprises a flexible sheath with an inside surface and an outside surface, wherein the sheath defines a lumen, a center support wire extending through the lumen, a first stiffening member extending from a first intermediate point on the tubular body to a second intermediate point on the tubular body, a second stiffening member extending from a third intermediate point on the tubular body to a fourth intermediate point on the tubular body, wherein the first stiffening member is attached to the inside surface of the sheath and the second stiffening member is attached to the center support wire.